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LSPREV.C
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1989-08-30
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/* Copyright (c) 1989 Citadel */
/* All Rights Reserved */
/* #ident "lsprev.c 1.1 - 89/07/03" */
#include <errno.h>
#include "lseq_.h"
/*man---------------------------------------------------------------------------
NAME
lsprev - previous lseq record
SYNOPSIS
#include <lseq.h>
int lsprev(lsp)
lseq_t *lsp;
DESCRIPTION
The lsprev function retreats the cursor of lseq lsp to the previous
record. If the cursor is currently null, it will be moved to the last
record. If the cursor is currently on the last record, it will be
moved to null. If lsp is empty, the cursor will remain set to null.
lsprev will fail if one or more of the following is true:
[EINVAL] lsp is not a valid lseq pointer.
[LSELOCK] lsp is not locked.
[LSENOPEN] lsp is not open.
SEE ALSO
lscursor, lsfirst, lslast, lsnext.
DIAGNOSTICS
Upon successful completion, a value of 0 is returned. Otherwise, a
value of -1 is returned, and errno set to indicate the error.
------------------------------------------------------------------------------*/
int lsprev(lsp)
lseq_t *lsp;
{
int rs = 0;
errno = 0;
/* validate arguments */
if (!ls_valid(lsp)) {
errno = EINVAL;
return -1;
}
/* check if not open */
if (!(lsp->flags & LSOPEN)) {
errno = LSENOPEN;
return -1;
}
/* check if not locked */
if (!(lsp->flags & LSLOCKS)) {
errno = LSELOCK;
return -1;
}
/* move cursor */
if (lsp->clspos == 0) {
lsp->clspos = lsp->lshdr.last;
} else {
lsp->clspos = lsp->clsrp->prev;
}
/* read in new current record */
if (lsp->clspos == 0) {
ls_rcinit(lsp, lsp->clsrp);
} else {
rs = ls_rcget(lsp, lsp->clspos, lsp->clsrp);
if (rs == -1) {
LSEPRINT;
return -1;
}
}
errno = 0;
return 0;
}